The invention provides a STATCOM (Static Synchronous Compensator) chain element unit bypass device and a control system. The bypass device is arranged in a chain element unit and comprises a circuit breaker with an electric operating mechanism. The input end and the output end of the circuit breaker are respectively connected with two AC ends of an H-bridge circuit of the chain element unit. When the circuit breaker is closed, the chain element unit can be bypassed from the STATCOM. The bypass device is simple in structure, few in components, low in cost, and convenient in mounting, operation and maintenance; the volume of the STATCOM can be reduced; and the power density and the reliability of the chain element unit are improved.